1. The Field of the Invention
This invention relates generally to the field of electrical connector systems for electrical components. In particular, embodiments of the present invention relate to a heat sink structure associated with a cage body that is adapted to receive low-profile, user-removable, electronic modules that interface with a port of a host device.
2. The Related Technology
Fiber optics are increasingly used for transmitting voice and data signals. As a transmission medium, light provides a number of advantages over traditional electrical communication techniques. For example, light signals allow for extremely high transmission rates and very high bandwidth capabilities. Also, light signals are resistant to electromagnetic interferences that would otherwise interfere with electrical signals. Light signals also provides a more secure signal because it does not allow portions of the signal to escape from the fiber optic cable as can occur with electrical signals in wire-based systems. Light signals also can be conducted over greater distances without the signal loss typically associated with electrical signals on copper wire.
While optical communications provide a number of advantages, the use of light as a transmission medium presents a number of implementation challenges. In particular, the data carried by light signal must be converted to an electrical format when received by a device, such as a network switch. Conversely, when data is transmitted to the optical network, it must be converted from an electronic signal to a light signal. Transmission of optical signals are typically implemented using a transceiver module at both ends of a fiber optic cable. Each transceiver module typically contains a laser transmitter circuit capable of converting electrical signals to optical signals, and an optical receiver capable of converting received optical signals back into electrical signals.
Typically, a transceiver module is electrically interfaced with a host device, such as a host computer, switching hub, network router, switch box, computer I/O and the like, via a compatible connection port. Moreover, in some applications it is desirable to miniaturize the physical size of the transceiver module to increase the port density, and therefore accommodate a higher number of network connections within a given physical space. In addition, in many applications, it is desirable for the module to be hot-pluggable, which permits the module to be inserted and removed from the host system without interrupting electrical power. To accomplish many of these objectives, international and industry standards have been adopted that define the physical size and shape of optical transceiver modules to insure compatibility between different manufacturers. For example, in 1998, a group of optical manufacturers developed a set of standards for optical transceiver modules called the Small Form-factor Pluggable Transceiver MultiSource Agreement (SFP Transceiver MSA). In addition to the details of the electrical interface, this standard defines the physical size and shape for the SFP transceiver modules, and the corresponding module cage that is mounted on a printed circuit board at the host and receives the transceiver modules, so as to insure interoperability between different manufacturers' products.
As the protocols used in optical networks increase in native transmission speed, the heat generated by the transceivers typically increases. For instance, 10-Gigabit transceivers generally require heat dissipation mechanisms, whereas transceivers used with optical transmission of lower speeds may not require heat dissipation. The use of heat dissipation mechanisms, however, increases the complexity and cost of the transceiver/cage assembly and reduces the space that would otherwise be available for the functional optical and electrical components of the assembly.
In addition, it is desirable to obtain module cages that have a substantially planar top surface that permits a flat rock tool to be used to mount the cages to printed circuit boards. Specifically, when a component has a substantially planar top surface and has pins that are aligned with corresponding holes in the surface of a printed circuit board, a flat rock tool can be used to press the pins of the component into the corresponding holes. In contrast, components that are not planar or otherwise have irregular top surfaces are mounted to printed circuit boards using dies that are formed to correspond to the shape of the top surface. The use of such specialized dies is expensive and cumbersome compared with the relatively simple flat rock tools that can be used with components having planar top surfaces.